TY - JOUR
T1 - Potent agonists of growth hormone‐releasing hormone
T2 - Part I
AU - ZARANDI, MARTA
AU - SERFOZO, PETER
AU - ZSIGO, JOZSEF
AU - BOKSER, LAZARO
AU - JANAKY, TAMAS
AU - OLSEN, DONALD B.
AU - BAJUSZ, SANDOR
AU - SCHALLY, ANDREW V.
PY - 1992/3
Y1 - 1992/3
N2 - Analogs of the 29 amino acid sequence of growth hormone-releasing hormone (GH-RH) with agmatine (Agm) in position 29 have been synthesized by the solid phase method, purified, and tested in vitro and in vivo. The majority of the analogs contained desaminotyrosine (Dat) in position 1, but a few of them had Tyr1, or N-MeTyr1. Some peptides contained one or more additional L- or D-amino acid substitutions in positions 2, 12, 15, 21, 27, and/or 28. Compared to the natural sequence of GH-RH(1-29)NH2,[Dat1,Ala15]GH-RH(1-28)Agm (MZ-3-191) and [D-Ala2,Ala15]GH-RH(1-28)Agm (MZ-3-201) were 8.2 and 7.1 times more potent in vitro, respectively. These two peptides contained Met27. Their Nle27 analogs, [Dat1,Ala15,Nle27]GH-RH(1-28)Agm (MZ-2-51), prepared previously (9), and [D-Ala2,Ala15,Nle28]GH-RH(1-28)Agm (MZ-3-195) showed relative in vitro potencies of 10.5 and 2.4, respectively. These data indicate that replacement of Met27 by Nle27 enhanced the GH-releasing activity of the analog when the molecule contained Dat1-Ala2 residues at the N-terminus, but peptides containing Tyr1-D-Ala2 in addition to Nle27 showed decreased potencies. Replacement of Ser28 with Asp in multi-substituted analogs of GH-RH(1-28)Agm resulted in a decrease in in vitro potencies compared to the parent compound. Thus, the Ser28-containing MZ-2-51, and [Dat1-Ala15,D-Lys21,Nle27]GH-RH(1-28)Agm, its Asp28 homolog (MZ-3-149), possessed relative activities of 10.5 and 5.6, respectively. In vivo after the iv injection, the analogs [Dat1,Ala15,Nle27,Asp28]GH-RH(1-28)Agm (MZ-3-149), [Dat1,Ala15]GH-RH(1-28)Agm, (MZ-3-191) and [D-Ala2,Ala15]GH-RH(1-28)Agm (MZ-3-201) showed a potency equivalent to 7.6, 4.9 and 3.3 times that of GH-RH(1-29)NH2, respectively, at 5 min and 203, 4.3 and 1.7 times higher, respectively, at 15 min. After sc administration, analogs MZ-3-149, MZ-3-191, and MZ-3-201 were shown to be 63.7, 55.2 and 56.8 times more potent than the parent hormone at 15 min and 57.6, 60.6, and 42.6 times more active, respectively, at 30 min. In addition, MZ-3-149 had prolonged GH-releasing activity as compared to the standard, and proved to be more potent than MZ-2-51, the most active member of our previous series (8, 9). Our studies indicate that very potent GH-RH analogs can result from the combination of agmatine in position 29 with other substitutions.
AB - Analogs of the 29 amino acid sequence of growth hormone-releasing hormone (GH-RH) with agmatine (Agm) in position 29 have been synthesized by the solid phase method, purified, and tested in vitro and in vivo. The majority of the analogs contained desaminotyrosine (Dat) in position 1, but a few of them had Tyr1, or N-MeTyr1. Some peptides contained one or more additional L- or D-amino acid substitutions in positions 2, 12, 15, 21, 27, and/or 28. Compared to the natural sequence of GH-RH(1-29)NH2,[Dat1,Ala15]GH-RH(1-28)Agm (MZ-3-191) and [D-Ala2,Ala15]GH-RH(1-28)Agm (MZ-3-201) were 8.2 and 7.1 times more potent in vitro, respectively. These two peptides contained Met27. Their Nle27 analogs, [Dat1,Ala15,Nle27]GH-RH(1-28)Agm (MZ-2-51), prepared previously (9), and [D-Ala2,Ala15,Nle28]GH-RH(1-28)Agm (MZ-3-195) showed relative in vitro potencies of 10.5 and 2.4, respectively. These data indicate that replacement of Met27 by Nle27 enhanced the GH-releasing activity of the analog when the molecule contained Dat1-Ala2 residues at the N-terminus, but peptides containing Tyr1-D-Ala2 in addition to Nle27 showed decreased potencies. Replacement of Ser28 with Asp in multi-substituted analogs of GH-RH(1-28)Agm resulted in a decrease in in vitro potencies compared to the parent compound. Thus, the Ser28-containing MZ-2-51, and [Dat1-Ala15,D-Lys21,Nle27]GH-RH(1-28)Agm, its Asp28 homolog (MZ-3-149), possessed relative activities of 10.5 and 5.6, respectively. In vivo after the iv injection, the analogs [Dat1,Ala15,Nle27,Asp28]GH-RH(1-28)Agm (MZ-3-149), [Dat1,Ala15]GH-RH(1-28)Agm, (MZ-3-191) and [D-Ala2,Ala15]GH-RH(1-28)Agm (MZ-3-201) showed a potency equivalent to 7.6, 4.9 and 3.3 times that of GH-RH(1-29)NH2, respectively, at 5 min and 203, 4.3 and 1.7 times higher, respectively, at 15 min. After sc administration, analogs MZ-3-149, MZ-3-191, and MZ-3-201 were shown to be 63.7, 55.2 and 56.8 times more potent than the parent hormone at 15 min and 57.6, 60.6, and 42.6 times more active, respectively, at 30 min. In addition, MZ-3-149 had prolonged GH-releasing activity as compared to the standard, and proved to be more potent than MZ-2-51, the most active member of our previous series (8, 9). Our studies indicate that very potent GH-RH analogs can result from the combination of agmatine in position 29 with other substitutions.
KW - GH‐RH analogs
KW - growth hormone‐releasing hormone
KW - solid phase peptide synthesis
KW - structure‐activity relationships
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U2 - 10.1111/j.1399-3011.1992.tb00791.x
DO - 10.1111/j.1399-3011.1992.tb00791.x
M3 - Article
C2 - 1399259
AN - SCOPUS:0026562123
VL - 39
SP - 211
EP - 217
JO - International journal of protein research
JF - International journal of protein research
SN - 0367-8377
IS - 3
ER -